# Sluice

A sluice is a water channel that is controlled at its head by a gate. A sluice gate is traditionally a wooden or metal plate which slides in grooves in the sides of the channel.

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## Operation

Raising a sluice gate allows water to flow under it. (The term sluice gate refers to any gate that operates by allowing water to flow under it.) When a sluice gate is fully lowered, water sometimes spills over the top, in which case the gate operates as a weir.

Usually a mechanism drives the sluice gate up or down. This may be a simple, hand-operated, worm drive or rack and pinion drive, or it may be electrically or hydraulically powered.

The gates of a lock may work in a way similar to the way a sluice gate works, but traditional canal lock gates are hinged to swing like double doors.

## Flow calculation

The sluice flow rate formula is:

[itex]Q = AC\sqrt{2gh}[itex]

where:

• Q is the flow
• A is the area of the sluice
• g is the acceleration due to gravity on the Earth's surface (approx. 9.81 m/s²)
• h is the head across sluice
• C is the discharge coefficient (typically 0.61 for small depth ratios)

## Types of sluice gates

• flap sluice gate - a fully automatic type, which is controlled by the pressure head across it. It is a gate hinged at the top. When pressure is from one side, the gate is kept closed. A pressure from the other side opens the sluice when a threshold pressure is surpassed.
• vertical rising sluice gate - a plate sliding in the vertical direction, controlled by machinery.
• radial sluice gate - a structure, where a small part of a cylindrical surface serves as the gate, supported by radial constructions going through the cylinder's radius, continuing through to a counterweight.
• rising sector sluice gate - also a part of a cylindrical surface, which rests at the bottom of the chanel and rises by rotating around its centre.

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